Modelling of the conductance distribution at the eastern margin of the European Hercynides     

S. Kovacikova  V. Cerv  O. Praus 《Studia Geophysica et Geodaetica》2005,49(3):403-421

Magnetic variation data recorded at 143 sites in the period range of 1000–6000 seconds were used to model the conductance distribution in the eastern part of the Bohemian Massif (BM) and the West Carpathians (WCP). The region represents a contact zone of the Palaeozoic Hercynian and Tertiary Carpathian orogenic systems. Two anomalies in the distribution of the electrical conductivity were found. One with a simple two-dimensional feature is located approximately near the boundary of the Inner and Outer West Carpathians, but the other of a complicated three-dimensional character is at the eastern margin of the BM. We inverted the observed geomagnetic data for the conductance in a unimodal thin sheet embedded at a specific depth. The inversion algorithm minimises the parametric functional that sums the squared norm of the misfit and the stabilising functional, and employs conjugate gradient optimisation. To express the sharp tectonic boundaries, we employed a minimum gradient support functional, which is applied in areas with strong variations of the model parameters. The inversion results confirmed a quasi-linear character of the regional anomaly distinguishing the Carpathian plate and led to new insight into the anomaly over the eastern margin of the BM. According to the results of the modelling the anomaly is formed by several conductive belts intersecting the anomalous zone. These belts follow important faults, dividing the transition zone between the BM and the WCP into individual blocks.  相似文献   

Underplating in the middle-lower Yangtze Valley and model of geodynamic evolution:Constraints from geophysical data   总被引：3，自引：0，他引：3  

Lü Qingtian  HOU Zengqian  YANG Zhusen & SHI Danian Institute of Mineral Resources  Chinese Academy of Geological Sciences  Beijing  China 《中国科学D辑(英文版)》2005,48(7)

~~Underplating in the middle-lower Yangtze Valley and model of geodynamic evolution:Constraints from geophysical data1)East China petroleum Administration,1988(unpublished data). 1)Measurements of regional rock densities and magnetic parameters of Anhui Province(research report),Annul Geological and Mineral Bureau,1987(unpublished). 1)In this paper South China Block(SCB)includes the Yangtze block and Cathaysian block.In the Neoproterozoic the Yangtze block had been sutured to th…  相似文献   

Warming in Arctic intermediate and deep waters around Chukchi Plateau and its adjacent regions in 1999   总被引：3，自引：0，他引：3  

ZHAO Jinping  GAO Guoping & JIAO Yutian . First Institute of Oceanography  State Oceanic Administration  Qingdao  China  . Ocean University of China  Qingdao  China 《中国科学D辑(英文版)》2005,48(8):1312-1320

Warming in the Arctic Intermediate Water (AIW) has been reported in a series of articles in recent years. Prior to 1992, the water temperature of AIW off the Chukchi Continental Slope had never exceeded 0.5℃. Aagaard et al.[1] and Carmack[2] were the first to report that the temperature in AIW in the area in 1993 was close to 1℃, based on the data observed in a Canadian expedition. In 1994, the temperature of AIW around the Chukchi Sea and Mendeleyev Ridge again rose by at least an…  相似文献   

Conrad Deep, Northern Red Sea: Development of an early stage ocean deep within the axial depression     

A. Ehrhardt  C. Hübscher  D. Gajewski 《Tectonophysics》2005,411(1-4):19-40

The northern Red Sea represents a continental rift in its final stage and close to the following stage of seafloor spreading. Ocean deeps within the evaporites of the northern Red Sea seem to accompany this process and are thought to be surface expressions of first seafloor spreading cells. In 1999 during R/V Meteor cruise M44/3 a dense multichannel seismic and hydroacoustic survey was conducted in order to investigate the initial formation process of the Conrad Deep, a young northern Red Sea deep. Three seismic units were differentiated in the uppermost part of the Miocene evaporites and the Plio-Quaternary sediments. A weakness zone within the evaporites, oblique to the main extension direction of the Red Sea, led to a transtension process within the evaporites that opened the deep. Its formation is directly related to the emplacement of magmatic bodies in its vicinity and the focusing of the Red Sea extension to the axial depression. The Conrad Deep is an intra-evaporite basin that cannot be regarded as surficial expression of a basement structure as the low shear strength of the evaporites decouple the sediments from the basement. However, its position and shape in combination with the accompanying geophysical anomalies point to a strong correlation with the Red Sea rifting process.  相似文献   

The effects of three-dimensional structure on two-dimensional images of crustal seismic sections and on the interpretation of shear zone morphology     

R. W. Hobbs  B. J. Drummond  B. R. Goleby 《Geophysical Journal International》2006,164(3):490-500

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Three-dimensional seismic reflection investigation of the upper crustal Winagami sill complex of northwestern Alberta, Canada     

J. Kim Welford  Ron M. Clowes 《Geophysical Journal International》2006,166(1):155-169

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北祁连错沟-小长干矿带铜锌矿床 物化探异常特征及找矿     

黄力军  刘瑞德  陆桂福 《物探与化探》2006,30(3):203-206

错沟—小长干矿带是北祁连西段成矿区段内铜矿(点)分布最多的矿化密集区,区内已发现多处铜矿床及铜矿点。这些已知矿(点)大多为块状硫化物矿床,矿石品位较高,但矿体相对较小,寻找深部隐伏矿难度相应较大,文中以具有代表性的实例讨论区内矿床物化探异常特征及相应找矿问题。  相似文献   

Comparisons, processing and interpretation of the surveyed data by GMS-06 and other magnetotelluric sounding systems     

于鹏吴健生  王家林张新兵 《地震学报(英文版)》2006,19(5):596-600

In recent years, the data collecting and processing of magnetotelluric sounding （MT） have progressed greatly. How to improve the quality of field surveyed data and obtain the high quality parameters such as apparent resistivity and phase is the most important link during the overall flow. It is closely related to the signal-to-noise ratio of magnetic sensors, the resolution of data collecting units and relevant processing methods as well. Produced by Germany Metronix Measurement Instruments and Electronics Ltd., the new type multi-channel geophysical measurement system GMS-06 was already adopted and used by domeslic units such as Institute of Geology and Geophysics of Chinese Academy of Sciences and Tongji University. Based on the brief introduction of GMS-06, this paper will give the comparisons and analyses of the synchronous surveyed MT data by GMS-06, MMS-03 MT system which was also produced by Metronix and V5-2000 MT system produced by Canada Phoenix Geophysics Ltd.. Then the preliminary processing and interpretation results of the long period MT data observed by GMS-06 in the area of Shanghai and Zhejiang are also discussed in the paper.  相似文献   

台湾海峡南部一次5.0级地震的sPn震相分析   总被引：5，自引：1，他引：5  

洪星  叶雯燕  邵平荣  许江英 《地震地磁观测与研究》2006,27(1):26-31

运用Pn震相对齐测定sPn震相的方法分析了发生在台湾海峡南部的一次5．0级地震的 sPn震相,初步了解sPn震相的一些特征,并在不同地壳模型下用sPn-Pn的走时差计算了该地震的震源深度。结果表明:在该地震中,sPn震相特征明显;用Pn震相对齐测定sPn震相的方法可以快速、可靠地测定出sPn震相;用sPn-Pn的走时差计算震源深度时,不同模型计算出的结果相差不大。  相似文献   

Genetic algorithm in seismic waveform inversion and its application in deep seismic sounding data interpretation     

王夫运  张先康 《地震学报(英文版)》2006,19(2):163-172

A genetic algorithm of body waveform inversion is presented for better understanding of crustal and upper mantle structures with deep seismic sounding （DSS） waveform data. General reflection and transmission synthetic seismogram algorithm, which is capable of calculating the response of thin alternating high and low velocity layers, is applied as a solution for forward modeling, and the genetic algorithm is used to find the optimal solution of the inverse problem. Numerical tests suggest that the method has the capability of resolving low-velocity layers, thin alternating high and low velocity layers, and noise suppression. Waveform inversion using P-wave records from Zeku, Xiahe and Lintao shots in the seismic wide-angle reflection/refraction survey along northeastern Qinghai-Xizang （Tibeteau） Plateau has revealed fine structures of the bottom of the upper crust and alternating layers in the middle/lower crust and topmost upper mantle.  相似文献